Chapter 3: Node Reference–The Annotated VRML97 Reference Manual

Chapter 3: Node Reference Intro Anchor Appearance AudioClip Background Billboard Box Collision Color ColorInterpolator Cone Coordinate CoordinateInterpolator Cylinder CylinderSensor DirectionalLight ElevationGrid Extrusion Fog FontStyle Group ImageTexture IndexedFaceSet IndexedLineSet Inline LOD Material MovieTexture NavigationInfo Normal NormalInterpolator OrientationInterpolator PixelTexture PlaneSensor PointLight PointSet PositionInterpolator ProximitySensor ScalarInterpolator Script Shape Sound Sphere SphereSensor SpotLight Switch Text TextureCoordinate TextureTransform TimeSensor TouchSensor Transform Viewpoint VisibilitySensor WorldInfo The SphereSensor node maps pointing device motion into spherical rotation about the origin of the local coordinate system. The SphereSensor node uses the descendent geometry of its parent node to determine whether it is liable to generate events. The enabled exposed field enables and disables the SphereSensor node. If enabled is TRUE, the sensor reacts appropriately to user events. If enabled is FALSE, the sensor does not track user input or send events. If enabled receives a FALSE event and isActive is TRUE, the sensor becomes disabled and deactivated, and outputs an isActive FALSE event. If enabled receives a TRUE event the sensor is enabled and ready for user activation. The SphereSensor node generates events when the pointing device is activated while the pointer is indicating any descendent geometry nodes of the sensor's parent group. See '2.6.7.5 Activating and manipulating sensors' for details on using the pointing device to activate the SphereSensor. Upon activation of the pointing device (e.g., mouse button down) over the sensor's geometry, an isActive TRUE event is sent. The vector defined by the initial point of intersection on the SphereSensor's geometry and the local origin determines the radius of the sphere that is used to map subsequent pointing device motion while dragging. The virtual sphere defined by this radius and the local origin at the time of activation is used to interpret subsequent pointing device motion and is not affected by any changes to the sensor's coordinate system while the sensor is active. For each position of the bearing, a rotation_changed event is sent which corresponds to the sum of the relative rotation from the original intersection point plus the offset value. trackPoint_changed events reflect the unclamped drag position on the surface of this sphere. When the pointing device is deactivated and autoOffset is TRUE, offset is set to the last rotation_changed value and an offset_changed event is generated. '2.6.7.4 Drag sensors' provides more details. When the sensor generates an isActive TRUE event, it grabs all further motion events from the pointing device until it is released and generates an isActive FALSE event (other pointing-device sensors cannot generate events during this time). Motion of the pointing device while isActive is TRUE is termed a 'drag'. If a 2D pointing device is in use, isActive events will typically reflect the state of the primary button associated with the device (i.e., isActive is TRUE when the primary button is pressed and FALSE when it is released). If a 3D pointing device (e.g., wand) is in use, isActive events will typically reflect whether the pointer is within (or in contact with) the sensor's geometry. While the pointing device is activated, trackPoint_changed and rotation_changed events are output. trackPoint_changed events represent the unclamped intersection points on the surface of the invisible sphere. If the pointing device is dragged off the sphere while activated, browsers may interpret this in a variety of ways (e.g., clamp all values to the sphere or continue to rotate as the point is dragged away from the sphere). Each movement of the pointing device while isActive is TRUE generates trackPoint_changed and rotation_changed events. Further information about this behaviour may be found in '2.6.7.3 Pointing-device sensors', '2.6.7.4 Drag sensors', and '2.6.7.5 Activating and manipulating sensors.' EXAMPLE (click to run): The following example illustrates the SphereSensor node (see Figure 3-52). The first SphereSensor, SS1, affects all of the children contained by the first Transform node, and is used to rotate both the Sphere and Cone about the Sphere's center. The second SphereSensor, SS2, affects only the Cone and is used to rotate the Cone about its center. The third SphereSensor, SS3, acts as a user interface widget that rotates both itself (the Box) and the Sphere/Cone group. The fourth SphereSensor, SS4, acts as a user interface widget that rotates itself (the Cylinder) and the Cone: Source.


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Last Modified: April 18, 2016 @ 4:09 am